A quick and reliable technique for detection of rheumatoid factor has been developed. The method requires no elaborate equipment or expensive reagents. It is a coagulation technique in which one drop of IgG coated Staphylococcus aureus is mixed with one drop of patients serum. Agglutination is produced in 3 minutes, which is macroscopically easily readable. In laboratory study complete correlation was found with other commercial reagents.